Kaspersky has been the best overall, and it won't flood the computer with advertising spam.
You barely know it's there.
Panda was cheap and did a good job, but it flooded the computer with spam for panda products. Really irritating.
The Free antivirus (like avast, malware bytes, etc...etc...) leaves your security full of holes.
Loading multiple security programs, from different sources, creates system conflicts.
Systems with this installed frequently get attacked, and successfully corrupted...
The big issue is that it does not update itself, inviting new infections to pop up all the time.
And the multiple products are not designed to work together.
It is far far better to use a professional antivirus, as I said, something less than 4 cents a day.
You have new virus signatures updated all day long.
You have blocking of unauthorized connections.
But STILL, depending on your internet habits, you can be infected.
People who download "free" stuff...free screensaver pictures, free games, free icons, free apps,
you will still be attacked, no matter what antivirus you have.
People who let the little kids use the computer. You are just asking for it.
You simply have to change the habits, and develop better caution.
KNOW how these crooks attack, and avoid walking into it!